Blaise Agüera y Arcas, a former distinguished engineer at Microsoft, is joining Google. Agüera y Arcas originally joined Microsoft in 2006 after the software giant acquired his Seadragon startup. He was a key software architect who helped develop and build Microsoft’s Bing Maps service and its image-stitching Photosynth software. The New York Times reports that Agüera y Arcas will work on machine learning at Google, something Microsoft’s research teams have been focusing on heavily recently.

Agüera y Arcas describes the decision to leave Microsoft as "the hardest decision of my life" in a blog post confirming his departure. Microsoft’s "lead­er­ship has been consistently good to me over these past eight years, and it has been a time filled with cre­ativ­ity and growth and good friends," Agüera y Arcas says. "It’s painful to leave behind so many wonder­ful ongo­ing projects, and even more so to leave behind such a great team."

A key engineer on Bing Maps and Photosynth image-stiching

His departure comes just days after Microsoft shipped a new Photosynth preview to the web, which includes new methods of stitching photographs and imagery to create 3D scenes. Agüera y Arcas demonstrated Microsoft’s Photosynth work in a TED talk back in 2007. The demonstration wowed audience members with the idea of linking the world’s photos with software. Agüera y Arcas’ departure will be seen as a key loss for the software company as it continues to reorganize its employees around "devices and services."  A Microsoft spokesperson confirmed Agüera y Arcas' departure in a statement to the NYT, noting "he was a great colleague and we wish him the best in his future endeavors."

It’s rare for senior Microsoft employees to join Google, especially distinguished engineers. Microsoft previously sued Google after the company hired former vice president Kai-Fu Lee, and court filings at the time revealed the competitiveness between the two firms. Mark Lucovsky, a former distinguished Microsoft engineer, was named in the filings and claimed that Microsoft CEO Steve Ballmer threw a chair across the room after Lucovsky revealed he was leaving to work for Google. Microsoft's latest battles with Google are highlighted with the company's ongoing Scroogled campaign — a series of ads designed to undermine Google's policies and products.